[Invertebrate • 2016] Orientothele alyratus • A New Genus and New Species of Diplurid Spider (Araneae: Mygalomorphae: Dipluridae) from northeast India

A new diplurid genus and species is described from northeast India based on a single female specimen from Jampui hills. Orientothele gen. nov. is placed in the subfamily Diplurinae based on the presence of one row of teeth on the chelicerae. The new genus and species can be diagnosed from most diplurid genera in lacking lyra on the prolateral face of maxilla, paired claw with one row of teeth, maxilla with numerous cuspules, scopulae absent on all legs, and spermathecae consisting of two elongate stalks with bulbous receptacles at their tips which are bent inwards. Ischnothele indicola Tikader, 1969 is here treated as incertae sedis with regards to its generic placement in light of the discovery of Orientothele gen. nov.

Diagnosis.Orientothele gen. nov. is here placed in the subfamily Diplurinae based on the presence of one row of teeth on the chelicerae. The new genus and species can be diagnosed from most diplurid genera in lacking lyra on the prolateral face of the maxilla, paired claw with one row of teeth, maxilla with numerous cuspules, scopulae absent on all legs, and spermathecae consists of two elongate stalks with bulbous receptacles at their tips which are bent inwards. Male unknown.

Description. A medium sized spider in relation to members of this family reaching a total length of 17.2 mm excluding chelicerae length. All legs bearing three claws, superior tarsal claws with a single row of sigmoid dentition and inferior tarsal claw with three dentitions. Scopulae absent. Two pairs of spinnerets and the posterior lateral spinneret long and widely spaced. Apical segment of posterior lateral spinnerets entire, no pseudosegmentation seen. Metatarsi of all legs with distal preening combs. Chelicerae with 13 promarginal teeth in a row of teeth and with 28 basosomal teeth. Maxillary and labial cuspules present. Labio-sternal collar well developed. Sternum cordate and the posterior edge nearly separating coxa IV. Carapace smooth, glabrous, with soft golden setae. Caput low. Fovea transverse, short. Spermathecae consists of two elongate stalks with bulbous receptacles at their tips which are bent inwards. Spigots on posterior lateral spinnerets fused and flagelliform. Base of spigot smooth with undulating grooved surface. Filiform trichobothria 13–20 present in a row on tarsi of all legs and palp. Spines present on all legs including tarsi of all legs.

Distribution. Presently known from borders of Tripura and Mizoram in northeast India

Comparisons. The new genus cannot be placed in the known subfamilies following diagnosis provided by Raven (1985). However, with an amended diagnosis by Drolshagen and Bäckstam (2009) the new genus may be placed in the subfamily Diplurinae in bearing the synapomorphy of a single row of teeth on chelicerae. Within Diplurinae the Orientothele gen. nov. differs from Metriura in bearing a single row of teeth on superior tarsal claws (vs. 2 in Metriura), from Diplura, Trechona, and Harmonicon in lacking prolateral maxillary lyra (vs. absent in Diplura, Trechona, and Harmonicon).

Etymology. The proposed generic name is a compound work formed by the word ‘Oriento’ = Oriental referring to the location of the type locality and the later word is a term assigned to members of the family Dipluridae. The sex of the proposed name is masculine.

Description of holotype female NCBS AR142 ( Figure 1). Holotype in general good condition with an exposed ventral cavity from a dissection to retrieve spermathecae. The abdomen is laterally compressed likely an artifact of preservation. The posterior lateral spinnerets lack the apical segment which has been removed for scanning electron imaging.

Etymology. The specific epithet is a Latinized compound word for “alyrate” with a Latin suffix ‘us’ referring to the absence of lyra on the prolateral face of maxilla.